1. Field of the Invention
The present invention relates to a primer composition in which a substrate mounting an optical semiconductor device is caused to adhere to a cured material of an addition reaction curing silicone composition that encapsulates the optical semiconductor device, and an optical semiconductor apparatus using the same.
2. Description of the Related Art
Light-emitting diode (LED) lamp known as an optical semiconductor apparatus has LED as an optical semiconductor device, and is configured by encapsulating the LED mounted on a substrate with an encapsulant including a transparent resin. As the encapsulant encapsulating the LED, an epoxy resin-based composition has been generally used so far. However, when an epoxy resin-based encapsulant is used, cracking and yellowing are likely to be caused by an increase in heat value and a decrease in the wavelength of light that are accompanied by miniaturization of a semiconductor package and increased brightness of LED in recent years. The reliability may decrease.
In terms of excellent heat resistance, a silicone composition has been used as an encapsulant (e.g., Patent Document 1). In particular, an addition reaction curing silicone composition is suitable for an encapsulant for LED since it is cured by heating in a short time and has good productivity (e.g., Patent Document 2). However, the adhesion between a substrate mounting LED and an encapsulant including a cured material of the addition reaction curing silicone composition is not sufficient.
On the other hand, a polyphthalamide resin has been often used as a substrate mounting LED since the mechanical strength is excellent. Therefore, a primer useful for the resin has been developed (e.g., Patent Document 3). However, in LED that requires a high light amount, the heat resistance of polyphthalamide resin is not sufficient, and the resin is tarnished. Recently, ceramic typified by alumina having more excellent heat resistance than the polyphthalamide resin has been often used for a substrate. A substrate made of alumina ceramic is easily delaminated from the cured material of the addition reaction curing silicone composition.
Since a silicone composition generally has excellent gas permeability, it is likely to be affected by the outside environment. When LED lamp is exposed to sulfur compounds, exhaust gas, or the like in the air, the sulfur compounds or the like permeate a cured material of the silicone composition, and a metal electrode, especially an Ag electrode on a substrate encapsulated by the cured material is corroded with time and turns black. As a countermeasure for this phenomenon, a primer using a polymer of acrylate ester containing a SiH group, a copolymer with an acrylate ester, a copolymer with a methacrylate ester, a copolymer with an acrylate ester and a methacrylate ester (Patent Document 4), and a primer using a silazane compound or a polysilazane compound that has at least one silazane bond in the molecule (Patent Document 5) have been developed. However, a primer having all heat resistance, adhesion, and corrosion such as sulfuration resistance has not been developed.
As conventional techniques associated with the present invention, the above-described documents and the following documents (Patent Documents 6 to 8) can be exemplified.